System configured for applying a modifying agent to a non-equidimensional substrate

ABSTRACT

The present invention is related to systems and methods for modifying various non-equidimensional substrates with modifying agents. The system comprises a processing chamber configured for passing the non-equidimensional substrate therethrough, wherein the processing chamber is further configured to accept a treatment mixture into the chamber during movement of the non-equidimensional substrate through the processing chamber. The treatment mixture can comprise of the modifying agent in a carrier medium, wherein the carrier medium is selected from the group consisting of a supercritical fluid, a near-critical fluid, a superheated fluid, a superheated liquid, and a liquefied gas. Thus, the modifying agent can be applied to the non-equidimensional substrate upon contact between the treatment mixture and the non-equidimensional substrate.

RELATED APPLICATION

[0001] This application is a divisional application of pending U.S.patent application Ser. No. 09/677,336, filed Sep. 27, 2000 and isincorporated by reference.

CONTRACTUAL ORIGIN OF THE INVENTION

[0002] This invention was made with United States Government supportunder Contract No. DE-AC07-94ID13223, now Contract No. DE-AC07-99ID13727awarded by the United States Department of Energy. The United StatesGovernment has certain rights in the invention.

FIELD OF THE INVENTION

[0003] The present invention is related to systems and methods formodifying various non-equidimensional substrates with modifying agents.

BACKGROUND OF THE INVENTION

[0004] Methods have been developed for the coating or modification ofvarious substrates including metals, alloys, organometallics, salts,optical fibers, filaments, cables, glass fibers, graphite fibers,fiberglass, structural polymers, single strand polymers, filamentouspolymers, composites, and the like. For example, polystyrene is known tobe a good coating for glass optical fibers to increase durability. Thesecoatings, however, are generally applied in a variety of ways withchemical treatment processes. Some of these methods of chemicaltreatment (for coating, impregnation, surface modification, etc.)include solvent-based systems and melt-based systems. Additionally, withrespect to non-equidimensional substrates, thermoplastics and othercoatings have been applied by various methods.

[0005] Solvent-based chemical treatment systems can include organic orinorganic materials in solutions such as aqueous solutions wherein theorganic or inorganic material is dissolved, suspended, or otherwisedispersed in the solution. In the area of coating of glass fibers, U.S.Pat. Nos. 5,055,119, 5,034,276 and 3,473,950 disclose examples of suchchemical treatments. Typically, with chemical treatment of some of theprior art, solvents are used to lower the viscosity of the chemicaltreatment to facilitate wetting of the glass fibers. The solvent issubstantially unreactive with the other constituents of the chemicaltreatment and is driven out of the chemical treatment after the wettingof the glass fibers. In each process for applying solvent-based chemicaltreatments, an external source such as heat can be used to evaporate orotherwise remove the water or other solvent from the applied chemicaltreatment, leaving a coating of organic material on the glass fibers.With melt-based chemical treatment systems, thermoplastic-type organicsolids can be melted and applied to various fibrous structures. Again,in the area of glass coating, U.S. Pat. Nos. 4,567,102, 4,537,610,3,783,001 and 3,473,950 disclose examples of such melt-based chemicaltreatments of glass fibers. These methods and others have been used inthe prior art to coat various elongated materials including textileyarns, monofilaments, bundles of monofilaments, and fibrous structures.

[0006] Supercritical fluids have been used previously to coat elongatedmaterials such as fibers, metals, and the like. However, when suchsupercritical fluids have been used, they have typically been applied byone of a few methods. Several of these techniques involve theapplication of one or more modifying agent by batch soaking in anenclosed chamber. Other methods include processes based upon sprayingfrom a pressurized chamber through a narrow nozzle.

[0007] With regard to spray-on deposition, air pressure sprayers havebeen used to contain supercritical and near-critical fluids (carriers)containing coating material. Upon spraying of the fluid onto thesubstrate, the supercritical fluid carrying the coating material leavesthe high pressure environment and is exposed to a normal atmosphericenvironment. Thus, the supercritical fluid is exposed to low pressureand evaporates, leaving behind the coating material or modifying agentwhich modifies the substrate. Examples of typical spray depositions ofthe prior art include U.S. Pat. Nos. 4,582,731, 4,734,227, 4,734,451,4,970,093, 5,032,568, 5,213,851, and 5,997,956. Regarding supercriticalfluid batch processes, the substrate is typically immersed and then thepressure is dropped, depositing the coating. This is usually followed bya drying stage. In a related embodiment, fluorocarbon polymers can beused to enhance solubility of polar components in supercritical fluid.However, this is still a batch process.

[0008] Though the use of liquified gas, supercritical fluids, andnear-critical liquids and gases have been used to coat solid or otherfibrous substrates in the prior art, none presently known by theapplicant appear to provide a system and method for modifyingnon-equidimensional substrates in a continuous system that does notutilize spray-on or batch coating processes.

SUMMARY OF THE INVENTION

[0009] The present invention is drawn to a system configured forapplying a modifying agent to a non-equidimensional substrate. Thesystem comprises a processing chamber configured for applying amodifying agent to the substrate. A pair of end seals are also disclosedwhich can be configured for accepting the shape of thenon-equidimensional substrate to be coated. For example, if end sealsare used and the substrate is flat or sheet-like, then the seals shouldbe large enough and configured appropriately to accept the substrateinto the system. Preferably, the seals can be configured to generallymatch (in a slightly larger manner) the shape of the non-equidimensionalsubstrate such that seal fluids (if used) and process chamber fluidscannot substantially leak into the surrounding atmosphere. A passagewayis provided within the device configured for passing the substratethrough the first end seal, the processing chamber, and the second endseal in series. Though not required, at least one expansion chamber canbe disposed between each of the end seals and the processing chamber.

[0010] Additionally, a method of continuously modifying anon-equidimensional substrate with a modifying agent is disclosed. Themethod of modifying the non-equidimensional substrate comprising thesteps of: providing a treatment apparatus chamber having a passagewayconfigured to pass the non-equidimensional substrate entirelytherethrough; providing a treatment mixture comprising a modifyingcomposition in a carrier medium, wherein the carrier medium is selectedfrom the group consisting of a supercritical fluid, a near-criticalfluid, a superheated fluid, a superheated liquid, and a liquefied gas;passing the non-equidimensional substrate continuously through thepassageway; and flowing the treatment mixture into the passageway duringmovement of the non-equidimensional substrate through the passageway.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In the accompanying drawing which illustrates an embodiment ofthe invention:

[0012]FIG. 1 is a schematic representation of an embodiment of thesystem of the present invention; and

[0013]FIGS. 2, 3, and 4 show various embodiments of end seals that canbe used with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0014] Before the present invention is disclosed and described, it is tobe understood that this invention is not limited to the particularconfigurations, process steps and materials disclosed herein as thesemay vary to some degree. It is also to be understood that theterminology used herein is used for the purpose of describing particularembodiments only, and is not intended to be limiting as the scope of thepresent invention. The invention will be limited only by the appendedclaims and equivalents thereof.

[0015] It must be noted that, as used in this specification and theappended claims, singular forms of “a,” “an,” and “the” include pluralreferents unless the content clearly dictates otherwise.

[0016] For the purposes of this document, “non-equidimensionalsubstrate” can include any structure that can be fed through thecontinuous system of the present invention, which has anon-equidimensional cross-sectional footprint perpendicular to thedirection of travel. For example, a cylinder would be consideredequidimensional, whereas a square bar or ribbon would be considerednon-equidimensional. More specifically, metals, alloys, inorganics,organometallics, solid organics, natural fibers and natural materials,salts, minerals; structural, construction, and high-strength polymers;single-strand polymers, multiple strand polymers; filamentous, sheet orwoven materials or polymers; ribbon and ribbon-like materials, screensand screen-like materials, and the like, can be non-equidimensional asdefined herein. These and other materials can be of anynon-equidimensional cross-sectional shape or length, including, but notlimited to non-circular fibrous or filamentous materials, non-circularrods, sheets, bars, screens, textile and non-textile fabrics, layered orplied materials, mats, flat stock, square stock, channel stock, anglestock, corrugated material, cast molded, extruded formed or otherwiseirregular shaped materials, and the like. Additional examples caninclude multiple structures of circularly symmetrical structures (orotherwise equidimensionally cross-sectioned structures) arranged in aside-by-side, top-to-bottom, encircled about each other, or otherwisearranged in an adjacent manner so as to present a non-equidimensionalcross-sectional footprint, or facial print in the direction co-linear totravel through the device. Thus, structures arranged as such includingropes, wires, cables, yams, threads, circular rods, round stock,splines, and the like, are included within the scope of the presentinvention.

[0017] “Supercritical fluid” shall be defined as a carrier or acarrier/chemical modifier mixture which is at a temperature above itscritical temperature.

[0018] “Near-critical fluid” includes conditions where the carrier iseither at or below the critical temperature or pressure for the carrier(or carrier with the chemical modifier) wherein the properties of themixture are at a state where they begin to approach those of asupercritical fluid. Near-critical fluid can further be divided intosubcatagories “near-critical gas phase” and “near-critical liquid phase”depending on the state that the fluid is in. “Near-critical gas phase”exists at pressures either less than or equal to the critical pressureand less than the bubble point pressure with temperatures somewhat belowto above the critical temperature (0.9T_(c) and above). “Near-criticalliquid phase” is defined as the phase that exists at temperatures eitherless than or equal to the critical temperature and pressures eithergreater than or equal to the bubble point pressure of the carrier and/orthe carrier and the chemical modifier.

[0019] “Liquefied gas” includes all gases that are at a temperatureand/or pressure where they are in a liquid state, but can readily bechanged to a gaseous state by altering the temperature or pressure.

[0020] “Superheated fluid” shall be defined as all liquids that canreadily be changed to a gaseous state by reducing the pressure.Typically, this is a liquid which is heated above the temperature atwhich a change of state would normally take place without any change ofstate having occurred. An example would be pressurized water above 100°C. at sea level.

[0021] “Superheated liquid” shall be defined a liquid, which is heatedabove the temperature at which a change of state would normally takeplace, without said change of state having occurred. An example would bepressurized water above 100° C.

[0022] “Modifying agent” and “modifying composition” can be usedinterchangeably and shall include any substance used for chemical ornon-chemical modification of a substrate. Thus, organic coatings,inorganic coatings, reactive coatings, sensor coatings, catalyticcoatings, conductive coatings, material expanders, impregnators,extractors, surface functionalizers, and other modifiers are includedwithin the present definition.

[0023] “Fluid” or “critical fluid” used generically shall includesupercritical fluid, near-critical fluid, superheated fluid, asuperheated liquid, and liquefied gas, unless the context clearlydictates otherwise.

[0024] “Treatment mixture” or “process fluid” shall include any mixtureof a carrier (preferably a fluid carrier as defined above) and amodifying agent.

[0025] Turning now to FIG. 1, a schematic representation of the systemof the present invention is shown. A housing 12 is shown having aplurality of baffles 14 which define a series of openings 16 forallowing a non-equidimensional substrate 18 therethrough. The baffles 14can be adjustable for allowing various sizes and shapes of substrates topass through the system. Specifically, the substrate shown in FIG. 1 isa single edge view of a sheet-like substrate.

[0026] Three different types of chambers are shown which include endseals 20 a,b, expansion chambers 22 a,b,c,d,e,f, and a processingchamber 24 having a constricted medial region 32. The end seals 20 a,bare maintained at a desired pressure by a seal fluid using a seal fluidregulator 26. If the end seals are to be maintained at differentpressures, then at least one pressure regulator 40 can be used. Apositive flow 28 a,b of seal fluid is maintained within the end seals 20a,b such that any fluids within the device are not allowed tosubstantially leak into the atmosphere. Because the device is configuredfor non-equidimensional substrates, the end seals the openings can beconfigured to essentially match the substrate dimensions, with theopening being slightly larger than the dimensions of thenon-equidimensional substrate. Such configurations can be seen in theend views shown in FIGS. 2 to 4 below.

[0027] The processing chamber 24 is the chamber where the substrate ismodified by the modifying material. Essentially, a process fluidcomprised of a carrier (which can be a supercritical fluid, anear-critical fluid, a superheated fluid, a superheated liquid, or aliquified gas) and a modifying material (for coating or otherwisemodifying the substrate) are fed into the processing chamber 24 throughan injector 30. As the injector 30 injects the process fluid toward theconstricted area 32 of the processing chamber 24, the pressure drops andcauses carrier to release or precipitate out the modifying materialeffectuating the modification of the substrate. Though the processingchamber shown has a constricted region, this is not required. In fact,other chambers shapes can be used where the modification of thenon-equidimensional substrate can be modified, provided the a passagewayis provided through the entire chamber that allows for the continuousfeed of the non-equidimensional substrate. Additionally, though notrequired, a temperature regulator 42 can be present for temperaturecontrol of the process fluid.

[0028] The expansion chambers 22 a,b,c,d,e,f are used, in part, tocollect any seal fluid or processing fluid, i.e., carrier and/ormodifying material, and can be maintained at desired pressures(depending upon the pressure and/or temperature of each fluid and theconfiguration of the expansion chambers and/or baffles 14). In oneembodiment, expansion chambers 22 a,b,c can be used to ratchet up thepressure sequentially in preparation for applying a modifyingcomposition to the substrate. Thus, chamber 22 b can be a higherpressure than expansion chamber 22 a and a lower pressure than 22 c.Conversely, expansion chambers 22 d,e,f can be used to ratchet down thepressure for reentry of the substrate into ambient pressures. Thus,expansion chamber 22 e can have a higher pressure than expansion chamber22 f and a lower pressure than expansion chamber 22 d. Any process fluidor seal fluid injected into the system can be collected from theexpansion chambers 22 a,b,c,d,e,f and sent to a collection area 34through a series of conduits 36. If the desire is to recycle thetreatment mixture for further use, then the treatment mixture can besent to the injector 30 through a recycling line 38.

[0029] Turning now to FIGS. 2 to 4, various end views of devices of thepresent invention are shown. Each of these end views are configured toaccept a different shaped non-equidimensional substrates. FIG. 2 showsan end seal 20 having an opening 16 configured to accept a corrugatedsubstrate. FIG. 3 shows an end seal 20 having an opening 16 configuredto accept a U-shaped substrate. FIG. 4 shows an end seal 20 having anopening configured to accept a sheet-like substrate. The presentinvention can also be configured to accept other non-equidimensionalshapes.

[0030] With these figures in mind, various non-equidimensionalsubstrates can be modified according to the systems and methodsdisclosed herein. Specifically, the present invention is drawn to asystem for applying a modifying composition to a non-equidimensionalsubstrate. The system comprises a processing chamber configured forpassing the non-equidimensional substrate therethrough, wherein theprocessing chamber is further configured to accept a treatment mixtureinto the chamber during movement of the non-equidimensional substratethrough the processing chamber. The treatment mixture can comprise themodifying agent in a carrier medium wherein the carrier is preferablyselected from the group consisting of a supercritical fluid, anear-critical fluid, a superheated fluid, a superheated liquid, and aliquefied gas. The modifying agent can then be applied to thenon-equidimensional substrate upon contact between the treatment mixtureand the non-equidimensional substrate.

[0031] In one embodiment of the invention, the processing chamber canhave a first region, a second region, and a constricted medial regionbetween the first region and the second region. Thus, when the modifyingagent can be separated from the carrier medium upon a pressure drop whenthe treatment mixture is introduced into the constricted medial region.The pressure drop can cause the modifying agent to be applied to thesubstrate.

[0032] Though not required, the use of end seals, i.e., entry seal andexit seal, can produce desired results. For example, an entry seal thatessentially matches and is slightly larger than the non-equidimensionalsubstrate can be used to substantially prevent process fluid loss andmaintain an appropriate pressure within the system. Similarly, an exitseal can provide a similar function. Typically, the non-equidimensionalsubstrate can be removed from the exit seal at the same rate that thenon-equidimensional substrate is continuously fed into the chamberthrough the entry seal.

[0033] Appropriate non-equidimensional substrates can include sheet-likesubstrates, U-shaped substrates, angled substrates, corrugatedsubstrates, etc. If, for example, a sheet-like substrate is to bemodified by the system disclosed herein, then plates, ribbons, sheets,screens, and plied materials are among the possible candidates forcoating or otherwise modifying.

[0034] Expansion chambers can also be used with the present system. Ifexpansion chambers are used, at least one expansion chamber can bedisposed between the entry seal and the processing chamber, and at leastone expansion chamber can be disposed between the exit seal and theprocessing chamber. In such a configuration, the entry seal and the exitseal can be fluid filled chambers which maintain a pressure that is atleast slightly greater than the adjacent expansion chambers. Thus, thesystem can be maintained essentially isolated from the surroundingatmosphere. In one embodiment, the fluid pressure is maintained bycontinuous inflow of a gas. Though not required, the gas used in the endseals can be inert with respect to the treatment mixture so that theseal gas does not interfere with the process fluids.

[0035] A method of modifying a non-equidimensional substrate is alsodisclosed comprising providing a treatment apparatus chamber having apassageway configured to pass the non-equidimensional substrate entirelytherethrough; providing a treatment mixture comprising a modifyingcomposition in a carrier medium, wherein the carrier medium is selectedfrom the group consisting of a supercritical fluid, a near-criticalfluid, a superheated fluid, a superheated liquid, and a liquefied gas;passing the non-equidimensional substrate continuously through thepassageway; and flowing the treatment mixture into the passageway duringmovement of the non-equidimensional substrate through the passageway.

[0036] In one embodiment, the passageway comprises a first region, asecond region, and a constricted medial region between the first regionand the second region. Thus, the treatment mixture can be flowed throughthe constricted medial region during movement of non-equidimensionalsubstrate through the passageway such that the modifying composition isseparated from the carrier medium and applied to the non-equidimensionalsubstrate upon a pressure drop. In some instances, the pressure drop cancause a rapid expansion of the carrier.

[0037] In many circumstances, it may be desirable to remove the carriermedium and unused modifying composition from the passageway. The removalof the carrier medium can be controlled by pressure regulators, and theregulated pressures can be different from one expansion chamber to thenext. Thus, a removal step can be part of the system and methoddisclosed herein. Once removed, the carrier medium and the unusedmodifying composition can be recycled for reuse if desired.

[0038] Additionally, injectors can be used to infuse treatment mixturesor other process fluids into the processing chambers. The injector canbe configured to inject the process fluids tangentially,perpendicularly, or at any other functional angle. For example, atangentially angled injector could be used in a chamber having twolarger opposing regions, separated by a constricted medial region.Additionally, multiple injectors can be used to ensure that all surfacesof the non-equidimensional substrate can be appropriately modified.Alternatively, a perpendicular injector at close proximity to asubstrate could be used to impregnate the substrate with higher pressureinjections. In another embodiment, the processing chamber can utilize atreatment mixture comprised of the modifying agent and a carrier forapplying the modifying agent, wherein the carrier is selected from thegroup consisting of supercritical fluid, near-critical fluid,superheated fluid, a superheated liquid, and liquefied gas.

[0039] An extraction or collection chamber can be fluidly coupled to theprocessing chamber for periodically or continuously removing unusedmaterial, i.e., seal fluids, carrier, and/or modifying agents, from theprocessing chambers. If expansion chambers are present, then thecollection chamber can be fluidly connected to the processing chamberthrough the expansion chambers. If desired, the fluids collected in thecollection chambers can be recycled for further use. In some instances,a further processing step may be required as could be ascertained by oneskilled in the art.

[0040] The end seals can be gas (or other fluid) filled seals. However,gas filled seals are not the only functional seals that can be used. Forexample, these seals can simply be configured as a physical constrictionor other barrier that is functional with the present system. If a gasfilled seal is used, exemplary gases for use can include air, carbondioxide (CO₂), nitrogen (N₂), helium, argon, nitrogen dioxide (NO₂), orother compatible process solvents or fluids. In one embodiment, the gasused in the seals can be essentially inert to the modification processthat is occurring in the nearby processing chambers.

[0041] Any parameter can be used to separate the processing chamber fromthe exterior environment such as temperature, pressure, or chemical andsolvent selection. The end seals can either be controlled by a singlefluid compressor, or each seal can be individually controlled by its owncompressor, pressure regulator, or combination of compressor andpressure regulator. In either case, it is preferred that the gas (orfluid) pressure within all of the seals be at least slightly greaterthan the nearest chamber, i.e, expansion chamber or processing chamber,to prevent escape of the process fluids.

[0042] As mentioned, FIG. 1 shows three expansion chambers and a sealchamber on each side of the process chamber. However, more or less maybe required depending on the application and pressure requirements ofthe specific application. Thus, prior to entry or exit from the deviceto normal atmospheric pressure (or other desired exterior pressure), asmoother pressure transition from the pressure inside the device to thepressure outside the device can be effectuated. With some applications,heaters can be used to maintain temperatures in a specific chamber.Control of chamber pressures and temperature allows each processapplication to have its own unique set of pressure and temperatureconditions.

[0043] With respect to the substrates that can be used with the presentdevice, any functional non-equidimensional substrate is contemplated.However, some appropriate substrates can include woven textiles formingfabrics, metals, alloys, organometallics, composites, salts, groupsfibers, groups of filaments, groups of glass fibers, groups of graphitefibers, fiberglass, structural polymers, organic polymers, inorganicpolymers, glasses, ceramics, super cooled liquids, and combinationsthereof. Additionally, no matter what substrate is used, themodification can be in form of a coating, impregnation, expansion of thesubstrate, extraction from the substrate, functionalization of thesurface, forming of a composite, and other desirable modifications ascould be ascertained by one skilled in the art. If a coating is themodification being applied, then coatings such as organic coatings,inorganic coatings, reactive coatings, sensor coatings, catalyticcoatings, conductive coatings, and combinations thereof can beeffectuated.

[0044] In the area of textiles, a system for dying or sizing textileyarns has been disclosed that departs from typical batch processespreviously known. Specifically, U.S. Pat. No. 5,709,910, the entireteachings of which are incorporated herein by reference, disclosesmethods for applying textile treatment compositions to textilematerials. This system comprising a conduit member which includes apassageway having a first end, a second end, and a medial portion with aconstricted (narrowed) region. The passageway may include at least onebaffle having an opening therethrough. In the system, a yarn strand isthen moved through the passageway. A sizing agent or dye is dissolved ina supercritical fluid or liquified gas which is thereafter introducedinto the constricted region. As the supercritical fluid or liquified gasis forced through the constricted region, the pressure drops and thesupercritical fluid or liquified, gas changes in properties such thatdelivery of the treatment dye or sizing agent to the yarn iseffectuated. The textile strands or yarn that may be sized or dyedinclude any textiles yarns such as cottons, linens, polyesters, nylons,rayons, cotton blends, and the like. The textile yarns disclosed thereinare lower strength yarns that are comprised of a series of short strandfibers that are spun together to form longer yarn products. Thus, strayfibers are inevitable and thus, provides the need for the use oflubricants, i.e., sizing agents, described therein. The temporarylubricant acts to reduce the number of stray fibers that may be damagedby any high speed equipment that may be used in the process of preparingtextiles, as well as reduce the friction between textile fibers duringweaving. An additional function can include the strengthening of theyarn. Though such a system and method have been shown to be effectivefor the sizing and dying of yarns, no device or method is currentlyknown that utilizes a processing chamber to modify non-equidimensionalsubstrates a continuous feed system. Such a system allows for the use ofenhanced chemical and physical properties of fluids under supercritical,near-critical, superheated, and liquified gas conditions, includingsolvating power, to treat the listed substrates in a continuous,efficient manner without the use of such structures as nip rollers. Thedevice upon which the process is based also allows for the recovery ofprocess energy and fluids to minimize waste.

[0045] The chemical compositions that can be applied with the system ofthe present invention include both organic and inorganic materialsincluding various chemical reagents, monomers, polymers, etc. Thesechemicals include, but are not limited to, various types of inorganiccompounds, organic compounds, and polymeric materials includingacrylates, acrylic acid monomers, acrylic acid polymers, salts ofacrylic acid copolymers, salts of polyacrylic acid, polyacrylates,polyvinyl chlorides, polyvinyl acetate, polyvinyl alcohols, cellulosederivatives, alginates, gums and starches, polyamides, polyimides,urethanes, polyurethanes, synthetic and natural resin varnishes,lacquers, polyphosphazenes, polyesters, polystyrenes, silicones,epoxies, fluoropolymers, etc. Chemical materials can be appliedindividually, sequentially, or as mixtures. Generally, the chemicalmodifiers or coatings can be in the form of organic coatings, inorganiccoatings, reactive coatings, sensor coatings, catalytic coatings,conductive coatings, material expanders, impregnators, extractors,surface functionalizers, and other modifiers can be used with thepresent invention.

[0046] Turning to an individual discussion of the various type ofsubstrate modifications that can occur, various modification methods areexemplified. The process parameters used to modify a non-equidimensionalsubstrate, e.g., apply a coating, are highly dependent upon themodification material and the particular solvent used as the carrierfluid. Temperature and pressure, time of fluid exposure to the modifyingmaterial, and factors like turbulence, ultrasound, mechanical mixing,etc., can affect the solubility of the modifying material and rate atwhich the modifying material can be dissolved into the fluid. A suitablerange for temperature and pressure is that defined by the following:0.9T_(c)≦T≦2T_(c) where T and T_(c) are expressed in degrees Kelvin, and0.1P_(c)≦P≦20P_(c) where P and P_(c) are expressed in any suitablepressure units.

[0047] The first equation states that the useable operating temperature(T) for the solvent has a value equal to, or greater than 0.9 times thevalue of the critical temperature (T_(c)), and less than or equal to 2times the critical temperature. The second equation is similarly statesthat the useable operating pressure (P) for the solvent has a valueequal to, or greater than 0.1 times the value of the critical pressure(P_(c)), and less than or equal to 20 times the critical pressure. Ingeneral, it is desirable to saturate the fluid with the modifyingmaterial or dissolve an amount close to the saturation limit, but anylevel of solubilization will achieve the effect of substratemodification. In practice, such modifications are dependent upon thechoice of solvent and solute, and thus, the range can be quiteextensive. Two examples are given that illustrate this feature.

[0048] To impregnate a sheet of poly(methyl methacrylate) (PMM) withpyrene to make a chemical sensor, one would dissolve 0.001 mole % pyrenein supercritical carbon dioxide (within the temperature and pressureconditions established above) and expose the PMM to the supercriticalsolution. Note that this is an extremely dilute solution and themodification occurs well below saturation.

[0049] An example illustrating the opposite extreme where the solute isat 100 mole % (i.e. the solute is the solvent) would be the coating ofan optical disk with a poly-fluorinated hydrocarbon (PFH). In thisexample, one would bring the PFH to within the conditions describedabove and expose the disk to the solvent/solute to achieve the desiredcoating.

[0050] Useable concentrations for other solvent/solute mixtures areintermediate between the values given above and are largely governed bythe solubility of the solute in the particular supercritical fluid. Therange extends from those that have very small solubility to those thatare completely miscible. An example of the first is given above, whilean example of the latter would be the use of tributyl phosphate (TBP)dissolved in supercritical carbon dioxide to be used as adecontamination solvent. In this case the solvent (CO₂) can be used insmaller proportion than the TBP and even below 10 mole percent.

[0051] With these working conditions in mind, various modifications canbe discussed in greater depth. With respect to organic and inorganiccoatings, functional coatings intended to impart some physical attributeto the substrate being coated are included. Some physical attributes caninclude imparting corrosion resistance, degradation resistance, abrasionresistance, hardness, lubricity, light (or other radiation) reflectiveor absorptive properties, ductility, elasticity, material thickness,magnetic susceptibility, radiation degradation resistance, stress reliefor resistance, thermal tolerance, and other similar attributes. Anotherfunction might be to encapsulate the coated material to restrict ormodify the movement of chemicals across the coating. The nature of thesecoatings is that they are superficial and comprise a coating or barrierbetween the coated material and the external environment.

[0052] Organic modifiers or coatings can be comprised in majority orentirely of organic materials. Such organic coatings can includeoccluded particles or co-deposited organic materials or inorganicmaterials. In one embodiment, polystyrene in a fluid acetone can beapplied to woven glass cloth to increase durability. In anotherembodiment, varnish in a fluid paint thinner can be applied to sheetcopper or copper ribbons to impart electrical insulating properties. Inthese and other embodiments, urethane or latex with or withoutnano-sized titania can be applied during the coating process orsubsequent to coating and prior to drying of the organic, respectively.

[0053] Another coating type includes inorganic coatings. These coatingscan be comprised of a majority or entirely of inorganic or non-organicmaterials, though occluded or co-deposited organic materials or otherinorganic materials can also be present. Examples of inorganic coatingsinclude metal and non-metal oxides, silicon, sulfur, or phosphorus-basedpolymers that may include dopants comprised of metals, organometallics,inorganics, hetero-atomic organics, minerals, or salts. In one example,silicone in a fluid petrolium ether can be applied to graphite to imparta dielectric coating.

[0054] Reactive coatings refers to functional coatings intended toimpart chemical reactivity or a specific chemical nature to varioussubstrates, particularly with respect to otherwise inert or un-reactivematerials. Many coatings can be both reactive or non-reactive dependingupon the environment surrounding the coating or the specific applicationfor the coating. For example, in the prior art, polyvinyl alcohol hasbeen used as an un-reactive coating to temporarily lubricate a textilefibers. However, as part of the present invention, polyvinyl alcohol canbe used as a coating on linear gasket materials to impart chemicaldegradation resistance toward gasoline and other petroleum products.

[0055] Sensor coatings are those coatings that interact with thesurrounding environment in a manner that changes one or more of theirchemical or physical properties. This sensor characteristic can be usedto sense changing conditions in an environment. Sensor materials can bereactive or non-reactive (but interactive) with the environment. As anexample of a non-reactive (interactive) coating, pyrene in fluid toluene(carrier) can be applied to glass slides or optical disks to effect thelight transmittance characteristics of the glass disk in the presence ofexplosives. As an example of a reactive coating, polysulfones can beapplied via fluid toluene or methylene chloride to glass slides oroptical disks such that the sulfones react with acid or base media, andcan be used as sensors.

[0056] Catalytic coatings, or coatings that interact chemically with thesurrounding environment in a manner wherein the coating behaves as acatalyst in a chemical reaction, can also be formed. An example of acatalytic coatings includes the dissolving of silver chloride and abeta-diketone in fluid carbon dioxide. Thereafter the mixture isdirected onto a substrate in the presence of hydrogen. Silver metal willbe deposited onto the surface of the substrate and can behave as acatalyst. Additionally, chloroplatinic acid can be applied to carboncloth, mesh, or matting in accordance with the principals of the presentinvention. After such a deposition, sodium borohydride can be applied toreduce the platinum to the metallic state. Thus, the coating can be usedas a catalyst. Additionally, other salts, solvents, complexing agents,substrates and reducing agents can yield similar results.

[0057] Conductive coatings refers to functional coatings that arethermally or electrically conductive. This includes coatings that aremetallic, inorganic, organic, or polymeric in nature and/or composition.Metal coatings may be applied directly by coating the metal onto asubstrate, or formed indirectly by applying a reactive coatingcontaining the metal in a chemical state that can later be changed tomake the coating conductive. For example, a substrate can be coated witha metal-containing flux (e.g. lead in zinc chloride) in fluid alcohol,after which, the coating can be heated or exposed to a chemicalenvironment that would reduce the metal-containing flux to the metallicstate (lead in this case). This process would produce “tinned”substrates suitable for soldering applications. Alternatively, asubstrate can be coated with a sulfonated polystyrene in fluid acetone.Thus, when exposed to water, it will become electrically conductive. Itwould be appreciated to one skilled in the art that the use of othermetal salts, fluxes, solvents, polymers, etc., will give similarresults.

[0058] Generally, there are two broad categories of substratemodifications (outside of coating) that can be effectuated which includephysical and chemical modification. Physical modifications refers tothose modifications that are primarily characterized by, or made toenhance, physical characteristics of the substrate through applicationof the invention, but not through applying a coating per se. Examples ofwhich are included herein.

[0059] Expanded materials include substrates that can be passed througha device like unto the device described herein under fluid pressure,whereupon exiting a higher the pressure region and entering anotherlower pressure region can cause rapid expansion of the substrate as afluid is expanded out of the substrate. An example would be to pass aPlexiglas [poly(methyl methacrylate)] substrate through the devicepressurized with fluid methylene chloride and hexane, whereupon exitinginto a lower pressure region will cause expansion of the Plexiglas.

[0060] With regard to impregnation, suspended particulate material canbe forced to impregnate a substrate by applying the particulate underpressure as a suspension in a fluid through a constriction or other typeof opening that is at a near-contact distance from the substrate. Anexample would be to use nano-sized graphite particulate suspended influid mineral oil that is then applied under pressure to impregnatelow-density polyethylene. Alternatively, a metal salt can be dissolvedinto a fluid and applied to a substrate that has some solubility in thefluid. Then the metal salt can also be converted to the metallic stateby appropriate chemistry (reduction or oxidation), resulting in themetal being impregnated into the substrate. An example of this would beto dissolve silver chloride into fluid water acetone mixture and applythis mixture to a poly(methyl methacrylate) substrate. Next, bycontacting the coating with a hydrogen or sodium borohydride, reductionwill occur and reduce the silver to the metallic state while imbeddedwithin the substrate.

[0061] With respect to chemical modification, the chemicalcharacteristics of the substrate can be altered or enhanced. Examplesinclude extraction and surface functionalization. Extractions apply tothe removal of some component, such as a soluble component, from thesubstrate. An example would be to remove a plasticizer, monomer units,or unwanted oligomers from polymer substrates. One application would beto extract unwanted contaminants from soil or other environmentalmatrices such as removing crude oil from sand and soils where spillshave occurred by applying alcohol or hexane in fluid form to a soil asit passed through the device. With respect to surface functionalization,a process and resultant state wherein the surface of the substrate ischemically modified can be accomplished. An example includes the passingof a cellulose substrate through a device described herein and expose itto one or more of fluid nitric acid, phosphoric acid, sulfuric acid toproduce nitrated, phosphated, sulfated cellulose, respectively. Thenitrated cellulose could be used in explosives while the phosphated orsulfated cellulose could be used as ion-exchange material.

[0062] The current processes will provide coatings and othermodifications with superior properties because of improved adhesion,bonding, and chemical reactivity or extraction. Exposure to the fluidsduring the application processes can also exert a cleaning influence ona substrate, removing surface contaminants that detrimentally affect theultimate properties of the final product. It is anticipated that theseprocesses can reduce failure rates and defects, and products withsuperior properties, such as tensile strength can be produced.Additionally, these processes provide opportunities for application ofthermally labile or otherwise sensitive chemical compositions to avariety of substrates.

[0063] While the invention has been described with reference to certainpreferred embodiments, those skilled in the art will appreciate thatvarious modifications, changes, omissions and substitutions can be madewithout departing from the spirit of the invention. It is intended,therefore, that the invention be limited only by the following claimsconstrued as broadly as applicable law allows including all properequivalents thereof.

We claim:
 1. A system for applying a modifying composition to anon-equidimensional substrate, comprising: a processing chamberconfigured for passing the non-equidimensional substrate therethrough,said processing chamber being further configured to accept a treatmentmixture into the chamber during movement of the non-equidimensionalsubstrate through the processing chamber, said treatment mixturecomprising the modifying agent in a carrier medium, said carrier mediumbeing selected from the group consisting of a supercritical fluid, anear-critical fluid, a superheated fluid, a superheated liquid, and aliquefied gas, said modifying agent being applied to thenon-equidimensional substrate upon contact between the treatment mixtureand the non-equidimensional substrate.
 2. A system as in claim 1 whereinthe processing chamber further comprises a first region, a secondregion, and a constricted medial region between the first region and thesecond region, and wherein the modifying agent is separated from thecarrier medium upon a pressure drop when the treatment mixture isintroduced into the constricted medial region, such that the modifyingagent is applied to the substrate.
 3. A system as in claim 2 furthercomprising an entry seal that essentially matches and is slightly largerthan the non-equidimensional substrate.
 4. A system as in claim 3further comprising an exit seal that essentially matches and is slightlylarger than the non-equidimensional substrate.
 5. A system as in claim 1wherein the non-equidimensional substrate is selected from the groupconsisting of sheet-like substrates, U-shaped substrates, corrugatedsubstrates, and angled substrates.
 6. A system as in claim 5 wherein thesheet-like substrate is selected from the group consisting of a plate, aribbon, a sheet, a screen, and a plied material.
 7. A system as in claim4 wherein the non-equidimensional substrate is removed from the exitseal at the same rate that the non-equidimensional substrate iscontinuously fed into the chamber through the entry seal.
 8. A system asin claim 1 further comprising at least one expansion chamber disposedbetween the entry seal and the processing chamber, and at least oneexpansion chamber between the exit seal and the processing chamber.
 9. Asystem as in claim 8 wherein the entry seal and the exit seal are fluidfilled chambers which maintain a pressure that is at least slightlygreater than the adjacent expansion chambers.
 10. A system as in claim 9wherein the pressure is maintained by continuous inflow of a gas.
 11. Asystem as in claim 10 wherein the gas is inert with respect to thetreatment mixture.
 12. A system as in claim 1 wherein pressure iscontrolled in the processing chamber by a pressure regulator.
 13. Asystem as in claim 1 wherein the temperature is controlled in theprocessing chamber by a temperature regulator.
 14. A system as in claim1 further comprising a substrate feed controller configured forcontrolling the speed at which the substrate is passed through thesystem.
 15. A system as in claim 4 wherein the entry end seal and theexit seal are adjustable to various sizes for accepting varioussubstrates for modification.